TY - JOUR AB - Brainwaves have demonstrated to be unique enough across individuals to be useful as biometrics. They also provide promising advantages over traditional means of authentication, such as resistance to external observability, revocability, and intrinsic liveness detection. However, most of the research so far has been conducted with expensive, bulky, medical-grade helmets, which offer limited applicability for everyday usage. With the aim to bring brainwave authentication and its benefits closer to real world deployment, we investigate brain biometrics with consumer devices. We conduct a comprehensive measurement experiment and user study that compare five authentication tasks on a user sample up to 10 times larger than those from previous studies, introducing three novel techniques based on cognitive semantic processing. Furthermore, we apply our analysis on high-quality open brainwave data obtained with a medical-grade headset, to assess the differences. We investigate both the performance, security, and usability of the different options and use this evidence to elicit design and research recommendations. Our results show that it is possible to achieve Equal Error Rates as low as 7.2% (a reduction between 68–72% with respect to existing approaches) based on brain responses to images with current inexpensive technology. We show that the common practice of testing authentication systems only with known attacker data is unrealistic and may lead to overly optimistic evaluations. With regard to adoption, users call for simpler devices, faster authentication, and better privacy. AU - Arias-Cabarcos, Patricia AU - Fallahi, Matin AU - Habrich, Thilo AU - Schulze, Karen AU - Becker, Christian AU - Strufe, Thorsten ID - 48063 IS - 3 JF - ACM Transactions on Privacy and Security KW - Safety KW - Risk KW - Reliability and Quality KW - General Computer Science SN - 2471-2566 TI - Performance and Usability Evaluation of Brainwave Authentication Techniques with Consumer Devices VL - 26 ER - TY - JOUR AU - Winkel, Fabian AU - Deuse-Kleinsteuber, Johannes AU - Böcker, Joachim ID - 48058 JF - IEEE Transactions on Reliability KW - Electrical and Electronic Engineering KW - Safety KW - Risk KW - Reliability and Quality SN - 0018-9529 TI - Run-to-Failure Relay Dataset for Predictive Maintenance Research With Machine Learning ER - TY - JOUR AB - Encrypting data before sending it to the cloud ensures data confidentiality but requires the cloud to compute on encrypted data. Trusted execution environments, such as Intel SGX enclaves, promise to provide a secure environment in which data can be decrypted and then processed. However, vulnerabilities in the executed program give attackers ample opportunities to execute arbitrary code inside the enclave. This code can modify the dataflow of the program and leak secrets via SGX side channels. Fully homomorphic encryption would be an alternative to compute on encrypted data without data leaks. However, due to its high computational complexity, its applicability to general-purpose computing remains limited. Researchers have made several proposals for transforming programs to perform encrypted computations on less powerful encryption schemes. Yet current approaches do not support programs making control-flow decisions based on encrypted data. We introduce the concept of dataflow authentication (DFAuth) to enable such programs. DFAuth prevents an adversary from arbitrarily deviating from the dataflow of a program. Our technique hence offers protections against the side-channel attacks described previously. We implemented two flavors of DFAuth, a Java bytecode-to-bytecode compiler, and an SGX enclave running a small and program-independent trusted code base. We applied DFAuth to a neural network performing machine learning on sensitive medical data and a smart charging scheduler for electric vehicles. Our transformation yields a neural network with encrypted weights, which can be evaluated on encrypted inputs in \( 12.55 \,\mathrm{m}\mathrm{s} \) . Our protected scheduler is capable of updating the encrypted charging plan in approximately 1.06 seconds. AU - Fischer, Andreas AU - Fuhry, Benny AU - Kußmaul, Jörn AU - Janneck, Jonas AU - Kerschbaum, Florian AU - Bodden, Eric ID - 31844 IS - 3 JF - ACM Transactions on Privacy and Security KW - Safety KW - Risk KW - Reliability and Quality KW - General Computer Science SN - 2471-2566 TI - Computation on Encrypted Data Using Dataflow Authentication VL - 25 ER - TY - THES AB - Reliability-adaptive systems allow an adaptation of system behavior based on current system reliability. They can extend their lifetime at the cost of lowered performance or vice versa. This can be used to adapt failure behavior according to a maintenance plan, thus increasing availability while using up system capability fully. To facilitate setup, a control algorithm independent of a degradation model is desired. A closed loop control technique for reliability based on a health index, a measure for system degradation, is introduced. It uses self-optimization as means to implement behavior adaptation. This is based on selecting the priorities of objectives that the system pursues. Possible working points are computed beforehand using model-based multiobjective optimization techniques. The controller selects the priorities of objectives and this way balances reliability and performance. As exemplary application, an automatically actuated single plate dry clutch is introduced. The entire reliability control is setup and lifetime experiments are conducted. Results show that the variance of time to failure is reduced greatly, making the failure behavior more predictable. At the same time, the desired usable lifetime can be extended at the cost of system performance to allow for changed maintenance intervals. Together, these possibilities allow for greater system usage and better planning of maintenance. AU - Meyer, Tobias ID - 9994 KW - dependability KW - reliability KW - behavior adaptation KW - self-optimization KW - multiobjective optimization KW - optimal control KW - automotive drivetrain KW - clutch system KW - reliability-adaptive system TI - Optimization-based reliability control of mechatronic systems ER - TY - CONF AB - The integrated modeling of behavior and reliability in system development delivers a model-based approach for reliability investigation by taking into account the dynamic system behavior as well as the system architecture at different phases of the development process. This approach features an automated synthesis of a reliability model out of a behavior model enabling for the closed loop modeling of degradation of the system and its (dynamic) behavior. The approach is integrated into the development process following Systems Engineering. It is based on standard models used in model-based development methodologies i.e. SysML or Matlab/Simulink. In addition to the theoretical description of the necessary steps the procedure is validated by an application example at two stages of the development process. AU - Hentze, Julian AU - Kaul, Thorben AU - Grässler, Iris AU - Sextro, Walter ID - 9974 KW - Design for X (DfX) KW - Product modelling / models KW - Robust design KW - Systems Engineering (SE) KW - Reliability T2 - ICED17, 21st International conference on enginieering design TI - Integrated modeling og behavior and reliability in system development ER - TY - JOUR AB - State-of-the-art mechatronic systems offer inherent intelligence that enables them to autonomously adapt their behavior to current environmental conditions and to their own system state. This autonomous behavior adaptation is made possible by software in combination with complex sensor and actuator systems and by sophisticated information processing, all of which make these systems increasingly complex. This increasing complexity makes the design process a challenging task and brings new complex possibilities for operation and maintenance. However, with the risk of increased system complexity also comes the chance to adapt system behavior based on current reliability, which in turn increases reliability. The development of such an adaption strategy requires appropriate methods to evaluate reliability based on currently selected system behavior. A common approach to implement such adaptivity is to base system behavior on different working points that are obtained using multiobjective optimization. During operation, selection among these allows a changed operating strategy. To allow for multiobjective optimization, an accurate system model including system reliability is required. This model is repeatedly evaluated by the optimization algorithm. At present, modeling of system reliability and synchronization of the models of behavior and reliability is a laborious manual task and thus very error-prone. Since system behavior is crucial for system reliability, an integrated model is introduced that integrates system behavior and system reliability. The proposed approach is used to formulate reliability-related objective functions for a clutch test rig that are used to compute feasible working points using multiobjective optimization. AU - Kaul, Thorben AU - Meyer, Tobias AU - Sextro, Walter ID - 9976 JF - SAGE Journals KW - Integrated model KW - reliability KW - system behavior KW - Bayesian network KW - multiobjective optimization TI - Formulation of reliability-related objective functions for design of intelligent mechatronic systems VL - Vol. 231(4) ER - TY - CONF AB - Intelligent mechatronic systems other the possibility to adapt system behavior to current dependability. This can be used to assure reliability by controlling system behavior to reach a pre-defined lifetime. By using such closed loop control, the margin of error of useful lifetime of an individual system is lowered. It is also possible to change the pre-defined lifetime during operation, by adapting system behavior to derate component usage. When planning maintenance actions, the remaining useful lifetime of each individual system has to be taken into account. Usually, stochastic properties of a fleet of systems are analyzed to create maintenance plans. Among these, the main factor is the probability of an individual system to last until maintenance. If condition-based maintenance is used, this is updated for each individual system using available information about its current state. By lowering the margin of error of useful lifetime, which directly corresponds to the time until maintenance, extended maintenance periods are made possible. Also using reliability-adaptive operation, a reversal of degradation driven maintenance planning is possible where a maintenance plan is setup not only according to system properties, but mainly to requirements imposed by maintenance personnel or infrastructure. Each system then adapts its behavior accordingly and fails according to the maintenance plan, making better use of maintenance personnel and system capabilities at the same time. In this contribution, the potential of maintenance plan driven system behavior adaptation is shown. A model including adaptation process and maintenance actions is simulated over full system lifetime to assess the advantages gained. AU - Meyer, Tobias AU - Kaul, Thorben AU - Sextro, Walter ID - 9949 KW - Adaptive systems KW - Reliability analysis KW - Availability KW - Adaptive control KW - Maintenance KW - Self-optimizing systems KW - Self-optimizing control KW - Stochastic Petri-nets T2 - Proceedings of the 9th IFAC Symposium on Fault Detection, Supervision and Safety for Technical Processes TI - Advantages of reliability-adaptive system operation for maintenance planning ER - TY - CONF AB - In order to increase mechanical strength, heat dissipation and ampacity and to decrease failure through fatigue fracture, wedge copper wire bonding is being introduced as a standard interconnection method for mass production. To achieve the same process stability when using copper wire instead of aluminum wire a profound understanding of the bonding process is needed. Due to the higher hardness of copper compared to aluminum wire it is more difficult to approach the surfaces of wire and substrate to a level where van der Waals forces are able to arise between atoms. Also, enough friction energy referred to the total contact area has to be generated to activate the surfaces. Therefore, a friction model is used to simulate the joining process. This model calculates the resulting energy of partial areas in the contact surface and provides information about the adhesion process of each area. The focus here is on the arising of micro joints in the contact area depending on the location in the contact and time. To validate the model, different touchdown forces are used to vary the initial contact areas of wire and substrate. Additionally, a piezoelectric tri-axial force sensor is built up to identify the known phases of pre-deforming, cleaning, adhering and diffusing for the real bonding process to map with the model. Test substrates as DBC and copper plate are used to show the different formations of a wedge bond connection due to hardness and reaction propensity. The experiments were done by using 500 $\mu$m copper wire and a standard V-groove tool. AU - Althoff, Simon AU - Neuhaus, Jan AU - Hemsel, Tobias AU - Sextro, Walter ID - 9868 KW - adhesion KW - circuit reliability KW - deformation KW - diffusion KW - fatigue cracks KW - friction KW - interconnections KW - lead bonding KW - van der Waals forces KW - Cu KW - adhering process KW - adhesion process KW - ampacity improvement KW - bond quality improvement KW - cleaning process KW - diffusing process KW - fatigue fracture failure KW - friction energy KW - friction model KW - heat dissipation KW - mechanical strength KW - piezoelectric triaxial force sensor KW - predeforming process KW - size 500 mum KW - total contact area KW - van der Waals forces KW - wedge copper wire bonding KW - Bonding KW - Copper KW - Finite element analysis KW - Force KW - Friction KW - Substrates KW - Wires T2 - Electronic Components and Technology Conference (ECTC), 2014 IEEE 64th TI - Improving the bond quality of copper wire bonds using a friction model approach ER - TY - JOUR AU - Hemsel, Tobias AU - Bornmann, Peter AU - Morita, Takeshi AU - Sondermann-Wölke, Christoph AU - Sextro, Walter ID - 9874 JF - Archive of Applied Mechanics KW - Reliability KW - Ultrasonic power transducers KW - FMEA SN - 0939-1533 TI - Reliability analysis of ultrasonic power transducers ER - TY - CONF AB - So-called reliability adaptive systems are able to adapt their system behavior based on the current reliability of the system. This allows them to react to changed operating conditions or faults within the system that change the degradation behavior. To implement such reliability adaptation, self-optimization can be used. A self-optimizing system pursues objectives, of which the priorities can be changed at runtime, in turn changing the system behavior. When including system reliability as an objective of the system, it becomes possible to change the system based on the current reliability as well. This capability can be used to control the reliability of the system throughout its operation period in order to achieve a pre-defined or user-selectable system lifetime. This way, optimal planning of maintenance intervals is possible while also using the system capabilities to their full extent. Our proposed control system makes it possible to react to changed degradation behavior by selecting objectives of the self-optimizing system and in turn changing the operating parameters in a closed loop. A two-stage controller is designed which is used to select the currently required priorities of the objectives in order to fulfill the desired usable lifetime. Investigations using a model of an automotive clutch system serve to demonstrate the feasibility of our controller. It is shown that the desired lifetime can be achieved reliably. AU - Meyer , Tobias AU - Sextro, Walter ID - 9884 KW - self-optimization reliability adaptive T2 - Proceedings of the Second European Conference of the Prognostics and Health Management Society 2014 TI - Closed-loop Control System for the Reliability of Intelligent Mechatronic Systems VL - 5 ER - TY - JOUR AU - Vidor, F.F. AU - Wirth, G.I. AU - Hilleringmann, Ulrich ID - 39483 IS - 12 JF - Microelectronics Reliability KW - Electrical and Electronic Engineering KW - Surfaces KW - Coatings and Films KW - Safety KW - Risk KW - Reliability and Quality KW - Condensed Matter Physics KW - Atomic and Molecular Physics KW - and Optics KW - Electronic KW - Optical and Magnetic Materials SN - 0026-2714 TI - Low temperature fabrication of a ZnO nanoparticle thin-film transistor suitable for flexible electronics VL - 54 ER - TY - CONF AU - Anwer, Jahanzeb AU - Meisner, Sebastian AU - Platzner, Marco ID - 10620 KW - fault tolerant computing KW - field programmable gate arrays KW - logic design KW - reliability KW - BYU-LANL tool KW - DRM tool flow KW - FPGA based hardware designs KW - avionic application KW - device technologies KW - dynamic reliability management KW - fault-tolerant operation KW - hardware designs KW - reconfiguring reliability levels KW - space applications KW - Field programmable gate arrays KW - Hardware KW - Redundancy KW - Reliability engineering KW - Runtime KW - Tunneling magnetoresistance T2 - Reconfigurable Computing and FPGAs (ReConFig), 2013 International Conference on TI - Dynamic reliability management: Reconfiguring reliability-levels of hardware designs at runtime ER - TY - CONF AB - To optimize the ultrasound irradiation for cavitation based ultrasound applications like sonochemistry or ultrasound cleaning, the correlation between cavitation intensity and the resulting effect on the process is of interest. Furthermore, changing conditions like temperature and pressure result in varying acoustic properties of the liquid. That might necessitate an adaption of the ultrasound irradiation. To detect such changes during operation, process monitoring is desired. Labor intensive processes, that might be carried out for several hours, also require process monitoring to increase their reliability by detection of changes or malfunctions during operation. In some applications cavitation detection and monitoring can be achieved by the application of sensors in the sound field. Though the application of sensors is possible, this necessitates modifications on the system and the sensor might disturb the sound field. In other applications harsh, process conditions prohibit the application of sensors in the sound field. Therefore alternative techniques for cavitation detection and monitoring are desired. The applicability of an external microphone and a self-sensing ultrasound transducer for cavitation detection were experimentally investigated. Both methods were found to be suitable and easily applicable. AU - Bornmann, Peter AU - Hemsel, Tobias AU - Sextro, Walter AU - Maeda, Takafumi AU - Morita, Takeshi ID - 9783 KW - cavitation KW - chemical reactors KW - microphones KW - process monitoring KW - reliability KW - ultrasonic applications KW - ultrasonic waves KW - acoustic properties KW - cavitation based ultrasound applications KW - cavitation intensity KW - change detection reliability KW - external microphone KW - malfunction detection reliability KW - nonperturbing cavitation detection KW - nonperturbing cavitation monitoring KW - process monitoring KW - self-sensing ultrasound transducer KW - sonochemical reactors KW - sonochemistry KW - ultrasound cleaning KW - ultrasound irradiation KW - Acoustics KW - Liquids KW - Monitoring KW - Sensors KW - Sonar equipment KW - Transducers KW - Ultrasonic imaging SN - 1948-5719 T2 - Ultrasonics Symposium (IUS), 2012 IEEE International TI - Non-perturbing cavitation detection / monitoring in sonochemical reactors ER - TY - CONF AB - Recent advances in information processing enable new kinds of technical systems, called self-optimizing systems. These systems are able to adapt their objectives and their behavior according to the current situation and influences autonomously. This behavior adaptation is non-deterministic and hence self-optimization is a risk to the system, e.g. if the result of the self-optimization process does not match the suddenly changed situation. In contrary, self-optimization could be used to increase the dependability by pursuing objectives like reliability and availability. In our preceding publications we introduced the so called multi-level dependability concept to cope with this new kind of systems (cf. [6]). This concept comprises the monitoring of the system behavior, the classification of the current situation, and the selection of the appropriate measure, if reliability limits are exceeded. In this paper we present for the first time experimental results. The dependability concept is implemented in the self-optimizing active guidance system of a railway vehicle. The test drives illustrate clearly that the proposed concept is able to cope with, e.g., sensor failures, and is able to increase the reliability and availability of the active guidance module. AU - Sondermann-Wölke, Christoph AU - Geisler, Jens AU - Sextro, Walter ID - 9763 KW - availability KW - dependability concept KW - multilevel dependability concept KW - railway vehicle KW - reliability KW - self optimizing active guidance system KW - self optimizing railway guidance system KW - situation classification KW - system behavior monitoring KW - optimal control KW - railways KW - reliability theory KW - self-adjusting systems SN - 0149-144X T2 - Reliability and Maintainability Symposium (RAMS), 2010 Proceedings - Annual TI - Increasing the reliability of a self-optimizing railway guidance system ER - TY - CONF AB - Self-optimizing mechatronic systems are a new class of technical systems. On the one hand, new challenges regarding dependability arise from their additional complexity and adaptivity. On the other hand, their abilities enable new concepts and methods to improve the dependability of mechatronic systems. This paper introduces a multi-level dependability concept for self-optimizing mechatronic systems and shows how planning can be used to improve the availability and reliability of systems in the operating stages. AU - Klöpper, Benjamin AU - Sondermann-Wölke, Christoph AU - Romaus, Christoph AU - Vöcking, Henner ID - 9736 KW - multilevel dependability concept KW - probabilistic planning KW - self-optimizing mechatronic systems KW - systems reliability KW - mechatronics KW - planning (artificial intelligence) KW - self-adjusting systems T2 - Computational Intelligence in Control and Automation, 2009. CICA 2009. IEEE Symposium on TI - Probabilistic planning integrated in a multi-level dependability concept for mechatronic systems ER - TY - CONF AB - EN: Although the use of new actuator technologies is quite enthusiastic, the realization of innovative systems based on these principles fails because of doubts in dependability. Until now, new working principles for actuators have not been systematically investigated in the means of dependability. Therefore we developed a proceeding for a dependability-oriented evaluation of technologies. This is shown in the case of shape memory alloy actuators. DE: Die Realisierung von Systemen mittels innovativer Aktortechnologien scheitert oftmals an der Skepsis gegenüber der Verlässlichkeit (Vertrauen in die zuverlässige und sichere Funktionalität der Technologie). Diese liegt darin begründet, dass neue Aktortechnologien bzw. die Integration von innovativen physikalischen Wirkprinzipen innerhalb neuer Aktorkonzepte bisher noch nicht systematisch im Kontext der Verlässlichkeit untersucht werden. Daher haben wir ein Vorgehen zur verlässlichkeitsorientierten Technologiebewertung entwickelt. Neben der detaillierten Darstellung des Vorgehensmodells wird es exemplarisch anhand von Formgedächtnislegierungen zur Entwicklung innovativer Antriebslösungen angewendet. AU - Müller, Thomas AU - Schiedeck, Florian AU - Hemsel, Tobias ID - 9570 KW - EN: Dependability KW - Reliability KW - Evaluation of Technology KW - Actuators KW - Shape Memory Alloys DE: Verl{\ T2 - 2. Tagung des DVM -- Arbeitskreis Zuverlässigkeit mechatronischer und adaptronischer Systeme: Absicherung der Systemzuverlässigkeit, Koblenz TI - Verlässlichkeitorientierte Technologiebewertung innovativer Aktortechnologien am Beispiel von Formgedächtnislegierungen ER -